Method of controlling an operation of a copy-cutting apparatus

ABSTRACT

A method of controlling an operation of a copy-cutting apparatus including a tracer for tracing automatically a pattern and a cutting gas torch interconnected to the tracer in a given relationship. Prior to the actual working, the tracer is manually moved with respect to the pattern along a given path and stores coordinates of operational points such as a piercing point, a copy start point, a copy end point, an intermediate point, a slow down point, etc. During the actual working the stored coordinates are read out to control the movement of the tracer in such a manner that until the tracer has reached a copy start point the copying apparatus is set in a position setting mode in which the tracer is moved under the control of the read out coordinates. After the tracer has reached the copy start point the copying apparatus is switched into a copying mode in which the movement of tracer along the pattern is controlled by detecting the pattern.

BACKGROUND OF THE INVENTION

The present invention relates generally to a copying system comprising atracer for tracing automatically a contour of a pattern to be traced anda working machine for effecting a given working for an object with aworking head being moved in conjunction with the tracer with a givenrelationship. More particularly it relates to a method for controllingan operation of the copying apparatus and an apparatus for carrying outthe method.

As an example of such a copying apparatus a copy-gas cutting apparatushas been known, the device comprises a tracer for tracing automaticallya contour of a pattern described on a template and a gas torch assemblyhaving at least one blowpipe for jetting a cutting oxygen flow againstan object such as a steel plate. In operation the steel plate is cut bythe oxygen flow from the torch, while the tracer follows the pattern onthe template in a mechanically contacting or photoelectricallynon-contacting manner. In this manner an article or workpiece having thesame shape as the pattern of template can be automatically cut out ofthe steel plate.

In the case of working the object, i.e. the steel plate with such a copygas-cutting apparatus, the tracer is at first positioned manually at apoint which is slightly remote from the pattern on the template and thegas torch assembly is operated to form a hole in the steel plate. Thisoperation is sometimes referred as piercing. Then the tracer is manuallymoved from the piercing point to a copy start point on the pattern,while the oxygen gas flow is ejected from the torch, i.e. the cuttingoperation is continued. After that the tracer traces automatically thetemplate and the steel plate is cut accordingly. When the tracer reachesa tracing end point, the ejection of cutting oxygen flow is stopped andthen the tracer is removed from the template. In the known copyingapparatus an operator must stay always near the apparatus to controlmanually the movement of the tracer and the operation of the gas torch.Therefore the known operation is very cumbersome and working efficiencyis very low. Particularly in the case of effecting a series ofoperations with using a plurality of patterns after the operation for apattern has been finished, the operator has to move the tracer to a nextpattern. Such treatment is quite hard to manage.

In order to obviate the above mentioned drawback there has been deviseda copying apparatus in which a tracer follows automatically from an endpoint of a pattern on a template to a start point of a next patternalong a guide line described on the template. In this case it isnecessary to prepare special templates on which guide lines have beendescribed and thus ordinary templates which have been used heretoforecould not be utilized. Since the template requires a very high accuracythe upmost care should be taken in manufacturing the same. Therefore itsprocess is quite complicated and results in high cost. Further in actualoperation it is sometimes undesirable to predetermine the piercingpoints, start points and end points in accordance with the shape andmaterial of objects to be worked, shape of pattern, arrangement ofpatterns in case of using a plurality patterns. In such a case thetemplate having the guide line previously described thereon could not beused and the operator must move the tracer manually or a new templatehaving a new guide line described thereon has to be prepared. In eithercases the working efficiency becomes lower to a great extent.

Further there has been developed a so-called numerical control system inwhich position of the working machine with respect to the object arepreviously set as numerical values which are then stored in a memory asa given program. The movement and operation of the working machine arecontrolled in accordance with the numerical data readout from thememory. It is apparent that such a numerical control system is verycomplicated in construction and expensive. Moreover the operation of themachine is exclusively controlled in accordance with the previouslydetermined program and thus could not be changed upon the actual workingand lacks flexibility. In other words the piercing points, start and endpoints of copying, etc. could not be simply changed in accordance withthe shape and material of object, the shape of the pattern andarrangement of patterns. In practice, the numerical control system isquite inconvenient for effectuating particular operations.

Upon operating the known copying apparatus the operator has to controlor command the operation of the working machine as well as the movementof the working machine into given positions. For instance, in the copygas-cutting machine after the tracer has been moved into a piercingpoint the gas torch is rendered operative to produce a jet of cuttingoxygen by operating a suitable member on a control panel. When thetracer has reached a copy end point the oxygen flow is stopped and thetracer is moved into a next piercing point. Then the cutting oxygen gasflow is again jetted from the gas torch. The above mentioned operationis rather cumbersome and results in a decrease in operation efficiency.In the numerical control system these operational functions of theworking machine can be previously stored in a memory, and during theworking the operational function of working machine can be controlled byreading out the command signals from the store. However as describedabove the numerical control system is very complicated and expensive andfurther the flexibility is lacking.

SUMMARY OF THE INVENTION

In the present invention a primary object is to provide a method ofcontrolling the movement of the tracer of a copying apparatus, in whichuse may be made of usual templates although the tracer need not be movedmanually during an actual working.

It is another object of the invention to provide a method of controllinga movement of a tracer of a copying apparatus, which can be carried outin a simple and economical manner.

It is still another object of the invention to provide a method ofcontrolling a movement of a tracer of a copying apparatus, in whichoperational points such as piercing points and copy start and end pointscan be preset prior to an actual working in a very simple manner inaccordance with shape and material of objects, shape and arrangement ofpatterns to be traced.

It is still another object of the invention to provide a method ofcontrolling a movement and operation of a copying apparatus, in whichoperational functions of a working machine at respective operationalpoints can be automatically controlled by means of a simple andinexpensive manner.

It is still another object of the invention to provide a method ofcontrolling the movement and operation of a copying apparatus, in whichthe amount of instructions about the operational functions of theapparatus to be stored in a memory can be reduced so as to make simplerthe storing operation and smaller the capacity of the memory.

The present invention also relates to an apparatus for controlling theoperation of a copying apparatus and has as an additional object toprovide a novel and improved controlling apparatus which has a simpleconstruction.

According to the invention a method of controlling a copying apparatusincludes a tracer for tracing automatically a contour of a pattern to becopied and a working machine for effectuating a given working operationfor an object to be worked upon being moved in conjunction with thetracer in a given relationship. The method comprises;

prior to an actual working,

a step for moving manually the tracer with respect to the pattern alonga desired path to detect coordinates of the tracer at respectiveoperational points such as a piercing point, a copy start point, a copyend point and the like and storing the coordinates in a memory; and

during an actual working operation,

a step for reading the stored coordinates out of the memory to generatea signal for controlling automatically the movement of tracer.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a plan view showing an embodiment of a gas cutting copyingmachine to which the control system according to the invention isapplied;

FIG. 2 is a plan view illustrating an embodiment of a control panelaccording to the invention;

FIG. 3 is a block diagram depicting an embodiment of an electriccircuitry for controlling the operation of the copying machine;

FIGS. 4 and 5 are plan views illustrating patterns to be traced by atracer for explaining the operation of the control system according tothe invention;

FIG. 6 is a plan view showing another embodiment of the control panelaccording to the invention;

FIG. 7 is a plan view illustrating patterns for explaining a repetitivecopying operation according to the invention;

FIG. 8 is a plan view depicting still another embodiment of the controlpanel according to the invention;

and

FIG. 9 is a plan view showing a pattern for explaining the operation ofthe control system according to the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 is a plan view showing an embodiment of a copy gas-cuttingapparatus an operation of which is to be controlled by the methodaccording to the invention. The entire apparatus rides on a pair ofrails 1a and 1b. A direction along which the rails extend is denoted asthe Y-direction and a direction perpendicular to the Y-direction as theX-direction. The apparatus comprises a main frame 2a and a subframe 2bon the bottom thereof are provided rollers (not shown) which are placedon the rails 1a and 1b. The main and subframes 2a and 2b areinterconnected to each other by means of a girder 3 which extends in theX-direction. A main carriage 4a and a subcarriage 4b are slidablyarranged on the girder 3 and are interconnected to each other by meansof a coupling lever 5. At a right hand end of the lever 5 aphotoelectric tracer 6 is secured. At a left hand portion of the lever agas torch assembly is provided which includes a plurality of gas torches7a, 7b and 7c. It should be noted that an optical axis of the tracer 6and an axis of each torch are aligned in the X-direction.

On the main frame 2a a Y-motor 8 is secured for driving the main frame2a and thus the tracer 6 and the torches 7a to 7c in the Y-direction. AY position detector 9 is also secured on the main frame 2a for detectinga position of the tracer 6 in the Y direction. Similarly on the maincarriage 4a an X-motor 10 is secured for driving the carriages 4a and 4band thus the tracer 6 and the torches 7a to 7c in the X-direction.Similarly an X position detector 11 is secured to the main carriage 4afor detecting a position of the tracer 6 in the X-direction. In thepresent embodiment each of the Y and X position detectors 9 and 11 isformed by a rotary encoder. It should be noted that any other type ofposition detector may be used.

The tracer 6 comprises a photoelectric sensor detecting a direction tobe traced and a projector for projecting a light spot onto a templateplaced on a template table 12 for indicating a position which iscurrently being traced. in this manner the operator can know a positionbeing traced by means of the light spot with respect to the pattern inthe template.

FIG. 2 shows an embodiment of a control panel 20 for storing coordinatesof operational points such as piercing point, copy start point, copy endpoint, etc. The control panel 20 may be provided at a suitable positionon the main frame 2a or may be arranged at a position remote from thecopying apparatus. In the latter case the control panel may beelectrically connected to the copying apparatus through a cable. In thisembodiment the control panel 20 comprises a piercing point presettingswitch, i.e., a push button 21, a copy start point presetting switch 22,a clear switch 23, a start switch 24 and a stop switch 25. The controlpanel 20 further comprises a manually operable timer of a dial type 26for presetting a preheating time, a switch 27 for prolonging a preheattime and a timer release switch 28 for ending the preheating within thepreset preheat time. Functions of each of these switches will bedescribed in later.

FIG. 3 is a block diagram illustrating an embodiment of an electriccircuitry for controlling the operation of the copying apparatusaccording to the invention. In FIG. 3 the above mentioned Y motor 8, Yposition detector 9, X motor 10 and X position detector 11 are shown.The control circuitry further comprises a steering motor 13 for drivinga sensor head provided in the tracer 6 and a steering angle detector 14for detecting a steering direction. The outputs from the control panel20 are connected to a control unit 20 and outputs from the detectors 9,11 and 14 are connected to a position detecting unit 31 which produces Xand Y coordinates of the tracer 6 and angle information of the tracingdirection. During a preparatory operation positional information atrespective positions is stored in a given storing position of a memory32 under the control of the control unit 30. During the actual workingoperation the information stored in the memory 32 is readout into aposition setting unit 33 under the control of the control unit 30 and isprocessed therein to generate information about the trajectory to befollowed by the tracer 6. The information thus formed is supplied toservo amplifiers 35, 36 and 37 by means of a switching unit 34 which iscontrolled by the control unit 30. The servo amplifiers 35, 36 and 37generate motor driving signals for the motors 8, 10 and 13, respectivelyto move the tracer 6 along a prederermined path and to direct the sensorhead of the tracer into a predetermined direction. While the tracer 6traces the pattern on the template, the output signal from the tracer 6is supplied to a copy control unit 38 an output signal is supplied tothe servo amplifiers 35, 36 and 37 through the switching unit 34.

The successive operations and functions of the copying apparatus will beexplained with reference to copying patterns shown in FIG. 4.

According to the invention prior to the actual working operation thetracer 6 is manually moved with respect to the patterns to be traced andcoordinates of operational points such as piercing point, copy startpoint and copy end point are previously stored in the memory 32. In FIG.4 a point O denotes an origin of X-Y coordinate system. Initially thetracer 6, has its optical axis preset at position O and Y and X up-downcounters provided in the position readout unit 31 are reset to zerocount. Then the tracer 6 is manually moved to a first piercing point P₀and X and Y coordinates thereof are detected by the position readoutunit 31. After it is confirmed that the light spot from the tracer 6impinges upon the desired piercing point P₀ the piercing pointpresetting switch 21 on the control panel 20 is depressed. Then the Xand Y coordinates readout by the unit 31 at this instance aretransferred to the memory 32 and are stored in a given address positionthereof together with information denoting that the point defined by thecoordinates is a piercing point. In this manner according to theinvention the piercing point P₀ can be set at any desired position withtaking into account the shape and material or property of the object tobe worked.

Next the tracer 6 is moved to a copy start point P₁ for a first patternA, in this case a circle. The copy start point presetting switch 22 onthe control panel 20 is depressed to store X and Y coordinates of therelated start point P₁ in the memory. At the same time a tracingdirection is denoted by manually operating a steering handle provided onthe tracer 6 to direct the tracer in a given direction. At this time theoutput from the angle detector 14 is read out by the unit 31 and theangle information is stored in the memory 32. In the instant example thepattern A is to be traced in the clockwise direction as shown by anarrow in FIG. 4.

Next the tracer 6 is moved to a second piercing point P₂ for a secondpattern B and the piercing point preset switch 21 is actuated to store Xand Y coordinates of the second piercing point P₂ in the related addressposition of memory 32. Further the tracer 6 is moved to a copy startpoint P₃ for this pattern B and X-Y coordinates of this point P₃ and theangle information for denoting the copying direction are stored in thememory 32. In this example the pattern B is also to be traced in theclockwise direction. Since both the patterns A and B are closedpatterns, i.e., those which can be described by one stroke and thetracer 6 will trace the patterns along closed paths or trajectories itis not necessary to preset any copy end point. That is to say when thetracer 6 will return the copy start point, it can be detected that thecopying operation for the pattern has been completed. If erroneouscoordinates are stored in the memory, they may be erased by operatingthe clear switch 23 on the control panel 20. That is, upon actuating theswitch 23 the last coordinates in the memory 32 can be removed.

After the preparatory operation has been finished as described above anactual working may be started. In the case of cutting an object by meansof the cutting gas torches 7a to 7c it is necessary to preheat theobject at the piercing point. In general the preheating time may varydependent upon many factors such as thickness and material of theobject, strength of preheating burn or hurt, and it is difficult todetermine one preheating time for all cases. In the present embodimentthe preheating time may be predetermined at will by presetting thepreheat timer 26 on the control panel 20. As will be explained hereinthe timer is actuated automatically when the tracer 6 reaches thepiercing points P₀ and P₂. Further the preheating time may be prolongedor shortened by operating the prolong switch 27 and release switch 28,respectively.

Upon initiation of the actual working operation the tracer 6 is firstset at the origin O and the start switch 24 on the control panel 20 isdepressed. Then the X and Y coordinates of the first piercing point P₀are readout from the memory 32 into the position setting unit 33. Inthis case since the switching unit 34 has been switched into a positionsetting mode the tracer 6 is moved automatically to the first piercingpoint P₀ at a high speed, e.g. 3,000 mm per minute. The position of thetracer 6 at any particular instance is always detected by the positiondetecting unit 31. When the tracer 6 arrives at the first piercing pointP₁ it is stopped thereat. Then the preheat timer 26 on the control panel20 is actuated by a command from the position setting unit 33 and thepreheating gases are ejected from the torches 7a to 7c. Immediatelybefore the preheating time has been finished, the cutting oxygen gasflows are jetted to form a hole in the object at the given piercingpoint P₀ . When the control unit 30 detects the completion of thepreheating cycle, the X and Y coordinates of the first copy start pointP₁ are read out from the memory 32 into the position setting unit 33which then generates a signal for moving the tracer 6 to the first copystart point P₁ at a predetermined cutting speed (50˜1,250 mm/minute).During this movement the steering angle data related to the point P₁ isalso read out from the memory 32 to drive the steering motor 13 to setthe sensor head of the tracer into the predetermined direction.

When it is detected that the tracer 6 has reached the first copy startpoint P₁, the control unit 30 sends a command to the switching unit 34which is then switched into the copying mode. Thereafter the tracer 6follows the contour of first pattern A under the control of the copycontrol unit 38 to cut the object into a shape corresponding to that ofthe pattern A.

In this manner the tracer 6 traces the pattern A in the clockwisedirection and returns to the first start point P₁. When this point isdetected, the ejection of the cutting oxygen flow is stopped. It shouldbe noted that the tracer 6 could not return to the point P₁ in anextremely accurate manner, but might deviate therefrom to a slightextent. Even in such a case the completion of the copying operation forthe pattern A has to be detected. For this purpose an error window witha center at the point P₁ and having a suitable size has beenpredetermined taking into account a width of a cut line, accuracies ofvarious portions, etc. In practice the error window may be a sequencehaving a side length of 0.5 to 1.5 mm. When the optical axis of thetracer 6 enters such an error window, it can be judged that the tracer 6has returned to the start point P₁. Then the cutting oxygen flow isstopped and the switching unit 34 is changed again into the positionsetting mode.

Next the coordinates of the point into which the tracer 6 should moveare read out from the memory 32 into the position setting unit 33 underthe control of the control unit 30. In this example the coordinates ofthe second piercing point P₂ for the second pattern B are read out. Theposition determining unit 33 judges that the readout coordinates of thepoint P₂ belong to the piercing point and generates a signal for movingthe tracer 6 into the point P₂ at high speed.

When the control unit 30 detects that the tracer 6 has arrived at thesecond piercing point P₂, it actuates the preheat timer 26 as describedabove with respect to the first piercing point P₁ to generate thepreheating gases from the torches 7a to 7c for a given preset timeperiod. At almost the end of this time period the cutting oxygen flowsare again ejected from the torches to effect the piercing.

Upon the completion of the preheating preset by the timer 26 thecoordinates of the copy start point P₃ for the pattern B is readout fromthe memory 32 into the position setting unit 33 and the tracer 6 ismoved to this point P₃ at the cutting speed. When the arrival of thetracer 6 at the point P₃ is detected, the control unit 30 switches theswitching unit 34 into the copying mode. Then the tracer 6 is driven bythe signal from the copy control unit 38 to cut the object in accordancewith the second pattern B. When the tracer 6 returns to the copy startpoint P₃, the ejection of cutting oxygen is stopped.

As explained above, according to the invention the actual workingoperation can be started merely by actuating the start switch 24 andthen the tracer 6 is automatically moved along the predetermined path tocut the object in accordance with the pattern. Therefore workingefficiency is improved to a great extent. Further the usual templatescan be used as they are and thus the control for the copying apparatuscan be carried out in a very inexpensive manner. Moreover the operationpoints such as piercing point and copy start point can be preset at willin the actual working place, so that the special skill of experiencedoperators can be adopted or utilized in the actual working and the veryefficient and accurate copying and working can be achieved.

FIG. 5 shows another example of a path to be traced by the tracer 6 inthe case of effecting the copying and working for a plurality ofpatterns C to F. Two patterns C and D are triangles, a pattern E acircle and a pattern F is a square. In this case three workpieces, i.e.,two triangular pieces and one rectangular piece with a circular openingare to be formed. Therefore the cutting operation is effected from apoint P₁ situated inside the circular pattern E, but outside thetriangular patterns C and D. At first the tracer 6 is moved into thefirst piercing point P₁ and its X and Y coordinates are stored in thememory 32 by actuating the piercing point presetting switch 21. Thencoordinates of a copy start point P₂ for the pattern C, a copy startpoint P₃ for the pattern D and a copy start point P₄ for the pattern Eare successively stored in the memory 32, while moving the tracerthrough these points. Next coordinates of a second piercing point P₅ anda copy start point P₆ for the pattern F are stored in succession.

In the actual working operation the tracer 6 is moved from the origin tothe first piercing point P₁ at the high speed and then the preheat timer26 is actuated to effect the piercing. After that the tracer 6 is movedtoward the copy start point P₂ at the cutting speed. When the tracer 6is detected to reach the point P₂, the switching unit 34 is switched inthe copy mode. Then the tracer 6 moves along the pattern C in theclockwise direction and arrives again at the start point P₂. Then theswitching unit 34 is switched into the position setting mode. At thesame time the coordinates of the point P₃ towards which the tracer 6should be moved are read out from the memory 32 into the positionsetting unit 33 in which this point P₃ is determined as a copy startposition. In this case the tracer 6 is moved into the start point P₃without stopping the cutting oxygen flow.

When the tracer 6 arrives at the position P₃, the copying mode is againselected and the copying and working is carried out along the contour ofthe pattern D. After full tracing along the closed pattern D the tracer6 again reaches point P₃ and the position setting mode is againselected. Then the tracer 6 is moved towards the next copying startpoint P₄ at the cutting speed. When the tracer arrives at point P₄, theswitching unit 34 is again set in the copying mode and the copying andworking is effected in accordance with the pattern E. When the tracerreturns to point P₄, the switching unit 34 is switched into the positionsetting mode.

At the same time the coordinates of the point P₅ towards which thetracer 6 should be moved are read out from the memory unit 32 into theposition setting unit 33 which detects that this point P₅ has beenstored as the piercing point. Therefore the ejection of the cuttingoxygen flow is temporarily stopped and the tracer 6 is moved to thepiercing point P₅ at the high speed. After the tracer 6 reaches thepoint P₅, the piercing is started to form a hole in the object atpiercing point P₅. After preheating has been finished the tracer 6 ismoved at the cutting speed to the copying start point P₆ for the patternF. When the tracer arrives at the point P₆, the copying mode is againselected and the working along the pattern F is performed.

As explained above according to the invention the working machine can bemoved from a pattern to another pattern with or without effecting thecontinuous cutting operation at the low or high speed. The copyingapparatus can be automatically controlled in the above mentioned mannerby detecting to what kind of functional point does a point to which thetracer should be moved belong. Therefore during the preparation periodit is not necessary to store a control command about the cutting oxygenflow, the tracer travelling speed, etc. Of course it is also notrequired for the operator to set these instructions during the actualworking.

FIG. 6 is a plan view showing another embodiment of the control panelaccording to the invention. A control panel 40 of this embodimentcomprises a clear switch 41, a piercing point presetting switch 42, acopy start point presetting switch 43, a start switch 44, a stop switch45, a preheat time prolonging switch 46 and a preheat timer releasingswitch 47 which are the same as those in the preceding embodiment shownin FIG. 2. In the present embodiment in order to preset the preheatingtime in a digital manner instead of the dial a numerically presettingbutton device 48 having ten keys and a clear button is provided. Afterthe preheat time presetting switch is depressed it is possible to presetany preheat time up to 99 seconds by operating the numericallypresetting button device 48. The preheat time thus preset is displayedin the preheat time display unit 50.

The control panel of this embodiment functions for repeating thecopy-working along the same pattern as will be explained hereinafterwith reference to FIG. 7. For this purpose the table 12 (FIG. 1) onwhich a template is to the placed is arranged movably in the Ydirection. Now it is assumed that a copy working in accordance with twopatterns G and H shown in FIG. 7 is effectuated repeatedly. Prior to theworking operation a piercing point P₁ and a copy start point P₂ for thefirst pattern G and a piercing point P₃ and a copy start point P₄ forthe second pattern H are stored successively as explained above. In thecase of repeating the copy-working it is necessary to return the tracer6 to the initial point P₁ after the first copy-working. Thus the tracer6 traces the following path. ##STR1##

After the first copy-working has finished the patterns G and H, i.e.,the template on which these patterns are described is moved in the Ydirection by a distance P and then the second copy-working is effectedfor thus shifted patterns G' and H'. In this case the tracer 6 has to bealso shifted in the Y direction by the same distance P. This distance Pcan be reset by means of the control panel 40 shown in FIG. 6. To thisend after a shift-distance presetting switch 51 has been depressed thedesired distance P can be introduced by operating the numericallypresetting button device 48 and then the distance P is displayed in adistance display unit 52. In response to the shift of the tracer 6 thecoordinates of all points are shifted in the Y direction by the distanceP at the start of the second copy-working. During the secondcopy-working the working operation is effected in accordance with thepoints P'₁ to P'₄ of the shifted patterns G' and H'. Further the numberof repeating times can be preset by actuating a repeat number presetingswitch 53. This repeat number can be displayed in a display unit 54. Inthis manner the copy-working operation can be repeatedly effected by thepreset repeat number for the shifted patterns G, H; G', H'; G", H" . . ., while every time the table 12 and the tracer 6 are shifted by thedistance P. In this embodiment since it is sufficient to store once thecoordinates of all points for the patterns G and H during thepreparation step the operation in the preparation is quite simple andthe capacity of the memory 32 can be made smaller.

In the above embodiments of the invention the path to be traced by thetracer 6 is preset during the preparation step and the tracer isautomatically controlled to follow the preset path. According to theinvention several other functions can be additionally provided.

FIG. 8 is a plan view illustrating another embodiment of the controlpanel which is provided with some additional functions. In FIG. 8portions corresponding to those of FIG. 6 are denoted by the samereference numerals as those used in FIG. 6. In this embodiment anintermediate point presetting switch 61, a copy end point presettingswitch 62, a continuous cutting switch 63, a slow down point presettingswitch 64 and a stage changing switch 65 are provided in the controlpanel. Functions of these switches will be explained hereinafter.

The intermediate point presetting switch 61 is used to preset a path tobe traced by the tracer 6 when the tracer is moved from a pattern to anext pattern without interrupting the ejection of cutting oxygen flow.This will be explained in detail with reference to a case in which thecopy-cutting should be effected continuously for two patterns I and Jshown in FIG. 9. A piercing point and a copy start point for the patternI are denoted by P₁ and P₂, respectively and a copy start point for thepattern J is indicated by P₄. If the tracer 6 is moved from the point P₂to the copy start point P₄ of the second pattern J along a path shown bya broken line in FIG. 9 without interrupting the cutting oxygen flowafter the copy-working for the first pattern I has been finished, thetorch would travel over a workpiece which has been cut in thecopy-working for the first pattern I and might injure the workpiece.Therefore the tracer could not be moved along the broken line. In such acase an intermediate point P₃ may be preset to store its coordinates inthe memory by actuating the intermediate point presetting switch 61. Itshould be noted that the intermediate point P₃ is selected so that thetracer can bypass the pattern I. After the copy-working for the firstpattern I has been completed the tracer 6 can be moved from the point P₂to the point P₄ via the point P₃ without interrupting the ejection ofcutting oxygen and the workpiece which has been formed by thecopy-working for the first pattern I can be protected against thecutting oxygen flow. In this case since the intermediate point P₃ is nota piercing point for the second pattern J this point P₃ should bediscriminated from the piercing point. To this end the intermediatepoint presetting switch 61 is provided separately from the piercingpoint presetting switch 42. In this manner the travelling of the tracercan be automatically controlled merely by presetting the coordinates offunctional points in such a manner that the tracer is moved from a pointto a next one with interrupting temporarily the cutting oxygen flow aswhen the second point has been set as the piercing point, while thetracer is moved at the cutting speed without interrupting the gas flowwhen the second point has been stored as the intermediate point.

The copy end point presetting switch 62 is used to preset and storecoordinates of a copy end point. If a pattern to be traced could not bedescribed with one stroke, the copying operation has to be interruptedat one or more given positions and then the copying operation is startedagain from one or more separate positions. In the preparation step ifcoordinates of a given point are stored as the copy end point byactuating the copy end point presetting switch 62, in the actual workingwhen the tracer reaches this point the copying operation is interruptedand the switching unit 34 is switched into the position setting mode. Ifa piercing point has been preset between the copy end point and a nextcopy start point, the ejection of cutting oxygen is automaticallyinterrupted at the copy end point and then the tracer 6 is moved to thenext point at the high speed. It should be noted that this next point isnot always the piercing point. On the contrary if the next copy startpoint has not been stored as the piercing point, the tracer is moved tothis point at the cutting speed without interrupting the oxygen flow.

In the repetitive copying operation which has been explained withreference to FIG. 7 the ejection of the cutting oxygen is interruptedduring the travelling of the table 12 and tracer 6 in the Y-direction tosuccessive positions. However depending upon a pattern to be traced itis preferable not to interrupt the cutting gas flow. For this purposethe control panel 60 has a continuous cut switch 63. As long as theswitch 63 is depressed the cutting oxygen flow is not interrupted evenafter the copy-working has been finished and the tracer and table aremoved in the Y-direction by the distance P at the cutting speed.

If a pattern has a sharp corner or use is made of a high speed plasmacutting, it is sometimes required to slow down the cutting speed justbefore the corner. To this end a slow down switch 64 is provided. In thepreparation step the tracer 6 is positioned at a point from which thecutting speed should be decreased and then the slow down pointpresetting switch 64 is actuated to store the coordinates of this pointas a slow down start point. In the actual working when the tracer isdetected to arrive at this point, the cutting speed is deccelerated at apredetermined rate from this point. When a predetermined speed has beenreached, the cutting speed is accelerated again at a predetermined rateto the ordinary cutting speed. In this manner the cutting speed can beautomatically decreased at the sharp corner to increase the workingaccuracy. In the above embodiment only the deccelerating point just infront of the corner is preset, but an accelerating point may be alsopreset, if any. In this case the tracer may trace the corner at thepredetermined low speed and then its moving speed is increased from theaccelerating point beyond the corner.

In the embodiment shown in FIG. 7 the shift distance P of the pattern inthe repetition mode is fixed to a constant length. But in some cases itis desirable to effect the repetitive copy-working at different positionof an object. In such a case it is necessary to move the template table12 to given positions to alter or change a cutting stage. In this caseif the table 12 and thus the tracer 6 is moved, the coordinates of thetracer might be changed arbitrarily and thus it is impossible to effectthe control with using the previously stored coordinates of the pointsas they are. In order to avoid such an inconvenience the origin O of X-Ycoordinates may be shifted by actuating the stage changing switch 65.When this switch 65 is depressed, the amount of shift of the tracer 6could not be detected by the position detecting unit 31. In this mannerthe origin of X-Y coordinates may be manually shifted into any desiredposition.

The invention is not limited to the embodiments explained above, butmany modification can be conceived within the scope of the invention.For example, in the above embodiments the present invention is describedas being applied to the control for the copy-cutting machine, but may bealso applied to other copying apparatus such as a copy-welding machine,and a copy-lathing machine. In the above embodiments the positionsetting unit 33 discriminates the kinds of the stored points to producethe signals for controlling the interruption of the cutting oxygen flow,the travelling speed, etc., but the present invention should not belimited to such embodiments. According to the principal concept of theinvention it is sufficient to control the tracer in such a manner thatit atuomatically travels along the predetermined path. In the abovecopying apparatus the tracer and the gas torch, i.e., the workingmachine are related to each other in the relationship of one-to-one, butmay be related differently therefrom.

The advantages according to the present invention may be summarized asfollows:

(1) Since any guide line for guiding the tracer from the piercing lineto the copy start point the ordinary templates can be used as they areand thus the copy-working can be carried out in an economical manner.

(2) After the operation points have been stored it is sufficient for theoperator to actuate the start switch and the operator is not necessaryto watch the operation of copying machine during the working step.Therefore the operation becomes quite simple and the working efficiencybecomes very high.

(3) As compared with the numerical control system the control methodaccording to the invention is rather simple and can be carried out intoeffect in an inexpensieve manner.

(4) The operational points such as the piercing point, the copy startpoint, etc. may be simply preset in the actual working place and duringthis presetting operation the skill of experienced person can be adoptedto a great extent.

(5) By discriminating the kinds of operational points it is possible toprovide the functions for applying the command signals with respect tothe travelling speed, the operation of the working machine, etc. as wellas the command signals for the travelling of tracer. In this manner theoperation efficiency can be further enhanced.

What is claimed is:
 1. A method of controlling the operation of acopying apparatus which includes a tracer for tracing automatically acontour of a pattern to be copied and a working machine having a workinghead movable in conjunction with the tracer in a given relationship foreffecting a given working operation for an object to be workedcomprising the steps of;prior to an actual working operation; moving thetracer manually with respect to the pattern to be traced to detectcoordinates of the tracer at respective operational points which includeat least a working start point, a copy start point, and a copy endpoint, and storing the coordinates thus detected in a memory; and duringthe actual working operation; reading the stored coordinates from thememory to control automatically the movement of said tracer in such amanner that until the tracer reaches a copy start point the copyingapparatus is set in a position setting mode in which the tracer is movedunder the control of the readout coordinates, and after the tracer hasreached the copy start point the copying apparatus is switched into acopying mode in which the movement of said working head is controlled bythe movement of the tracer which follows the pattern.
 2. A methodaccording to claim 1, wherein the pattern is that which can be describedwith one stroke and the copy start point is also used as the copy endpoint and when the tracer returns to the copy start point, the copyingapparatus is automatically switched into the position setting mode.
 3. Amethod according to claim 2, wherein the return of the tracer to thecopy start point is detected in such a manner that the tracer entersinto an error window having a center at the copy start point and apredetermined size.
 4. A method according to claim 1, wherein thepattern to be traced is shifted with respect to the copying apparatus bya given distance and the working operation for the object in accordancewith the pattern is repeated at respective shifted positions.
 5. Amethod according to claim 4, wherein said given distance is preset priorto the actual working operation.
 6. A method according to claim 5,wherein the coordinates of the operational points stored in the memoryare automatically shifted by the preset distance.
 7. A method accordingto claim 1, wherein a command signal for denoting a direction of thecopying movement is previously stored in the memory in relation to thecoordinates of the copy start point prior to the actual workingoperation and the command signal thus stored is read out during theactual working operation to control the direction of copying movement oftracer at the copy start point.
 8. A method according to claim 1,wherein an origin of the coordinates is shifted with respect to theobject during the actual working operation so that the same workingoperation is repeatedly effected in separate regions of the object.
 9. Amethod according to claim 1, wherein prior to the working operationcommand signals for denoting an operation of the working machine at theoperational points and during the movement between the successiveoperational points are stored in the memory in relation to thecoordinates at the operational points; andduring the actual workingoperation the command signals are read out from the memory together withthe coordinates of the related points to control automatically theoperation of the working machine.
 10. A method according to claim 9,wherein during the actual working operation the movement of the tracerand the operation of working machine are controlled in accordance withthe read out coordinates and command signals.